In semiconductor integrated circuit manufacturing, it is conventional to test integrated circuits (“IC's”) during manufacturing and prior to shipment to ensure proper operation. Wafer testing is a well-known testing technique commonly used in production testing of wafer-mounted semiconductor IC's, wherein a temporary electrical current is established between automatic test equipment (ATE) and each IC mounted on the wafer to demonstrate proper performance of the IC's. Components that may be used in wafer testing include an ATE test board, which is a multilayer printed circuit board that is connected to the ATE, and that transfers the test signals back and forth between the ATE and a probe card assembly. The probe card assembly (or probe card) includes a printed circuit board that generally contains several hundred probe needles (or “probes”) positioned to establish electrical contact with a series of connection terminals (or “die contacts”) on the IC wafer.
Known probe card assemblies include a probe card available from Kulicke and Soffa, Inc. of Willow Grove, Pa. Such probe cards comprise a printed circuit board, a probe head having a plurality of flexible probes, and a space transformer which electrically connects the probes to the printed circuit board. The space transformer may comprise a multi-layer ceramic substrate, or alternatively, a multi-layer organic substrate.
It is known to mount the probes to a substrate mounting surface of the space transformer using wire bonding or wedge bonding techniques well known to those of ordinary skill in the art of semiconductor manufacturing. Typically, the probes are mounted to electrically conductive, preferably metallic, bonding pads formed on the substrate through conventional plating or etching techniques.
One difficulty in the fabrication of probe cards is that the probes must be precisely positioned on the substrate mounting surface to provide both proper alignment and planarity of the probe tips. Using conventional probe mounting techniques, great care must be exercised to obtain proper alignment and planarity of the probe tips. As such, it would be desirable to provide an improved probe card and associated method of attaching the probes to the probe card which facilitates achieving proper alignment and planarity of the probe tips.